石墨烯新型制备技术及其在二氧化钛光阳极中的应用
发布时间：2018-08-06 13:42
【摘要】：染料敏化太阳能电池,因为低成本、高效率、易于制造等优点,具有很大的潜力成为规模化生产的新型太阳能电池。尽管已经实现13%的光电转换效率,从应用角度,仍然需要进一步提升效率。限制染料敏化太阳能电池效率提升的主要瓶颈在于,光阳极中光生电子在通过二氧化钛颗粒的传输过程中,由于纳米颗粒间的缺陷和弱连接,导致电子在传输过程中发生大量的复合反应,限制了电池的输出电流。为了改善纳米颗粒间的连接,提升光阳极对光生电子收集效率,从而实现更高的光电转换效率。石墨烯,一种性质稳定的二维纳米碳材料,因为具有高于二氧化钛数亿倍的电导率,被作为电荷传输材料引入到染料敏化太阳能电池光电阳极中。本课题主要探索绿色无毒条件下制备含有高导电性石墨烯并且成分均匀的石墨烯-二氧化钛复合物,并将其制成染料敏化太阳能电池的光阳极,用于提升光阳极中电子传输,提高电池效率。我们提出了一个简单方法,在温和条件下实现绿色环保的制备石墨烯-二氧化钛光阳极,在常温条件下使用维生素C作为还原剂,通过简单的搅拌和离心操作,将氧化石墨烯还原为石墨烯(RGO)从而制备成石墨烯-二氧化钛纳米复合材料。调整复合物中RGO的含量,制备成不同含量的RGO-TiO2光阳极。在具有相同薄膜厚度的情况下,0.75 wt.%RGO-TiO2复合物相比于普通二氧化钛颗粒提升了 30.2%的光电转换效率。RGO-TiO2复合光阳极在16μm厚度的情况时,能够得到最高的转换效率。此外,我们还研究了石墨烯尺寸对于电池效率的影响,发现使用较小的石墨烯能够改善染料吸附量,从而得到更高的转换效率。探讨了光阳极加入RGO后对电池各项参数的影响,更进一步研究了电池的电学性能,发现效率的提升来源于石墨烯改进了光生电子的传输能力,降低了复合反应的数量,延长了电子寿命。然而,还原法制备的石墨烯,因为在制备过程中,需要先氧化成为氧化石墨烯,再还原为石墨烯,而氧化过程和还原过程会在石墨烯片层内产生缺陷,导致石墨烯品质下降,降低导电性,最终限制了电池效率。为了解决上述问题,我们利用简单的液相超声剥离石墨,得到剥离石墨烯(EGS),然后混合TiO2纳米颗粒,制备EGS-TiO2复合光阳极。由于EGSL比常规的RGO具有更少的缺陷:EGS拉曼ID/IG～0.256远小于RGO～1.128,EGS可以实现更高的电子迁移率从而实现更高的导电性。经过实验测量EGS具有近两倍于RGO的电导率,并且功函数(4.51 eV)恰好处于二氧化钛和导电玻璃之间,有利于电子传递。EGS-TiO2光阳极实现了 8.24%的转换效率,对比相同的制备条件下的RGO-TiO2光阳极提升了 19%。效率的提升来自于EGS具有较少的面内缺陷,相比RGO或者只有TiO2的光阳极,可以具有更好的电导率实现更好的光电子传输。
[Abstract]:Dye-sensitized solar cells have great potential for large-scale production because of their advantages of low cost, high efficiency and easy to manufacture. Although 13% optoelectronic conversion efficiency has been achieved, there is still a need to further improve the efficiency from an application point of view. The main bottleneck limiting the efficiency improvement of dye sensitized solar cells is that the photogenerated electrons in the photoanode are due to the defects and weak connections between the nanoparticles during the transmission through the TIO _ 2 particles. A large number of complex reactions occur during the transmission of electrons, limiting the output current of the battery. In order to improve the connection between nanoparticles and improve the photoelectron collection efficiency of photoanode, thus achieving a higher photoelectric conversion efficiency. Graphene, a stable two-dimensional nano-carbon material, is introduced as a charge transfer material into the photoanode of a dye sensitized solar cell because of its conductivity hundreds of millions of times higher than titanium dioxide. In this paper, we mainly explore the preparation of graphene titanium dioxide complex containing high conductivity graphene and uniform composition under green nontoxic conditions, and make it into a dye sensitized solar cell photoanode, which is used to enhance electron transport in photoanode. Improve battery efficiency. We proposed a simple method to prepare graphene-titanium dioxide photoanode under mild conditions. Under normal temperature, vitamin C was used as reducing agent, and simple agitation and centrifugation were used to prepare graphene-titanium dioxide photoanode. Graphite-titanium dioxide nanocomposites were prepared by reducing graphene oxide to graphene (RGO). RGO-TiO2 photoanode with different content was prepared by adjusting the content of RGO in the complex. Under the condition of the same film thickness, the highest conversion efficiency can be obtained when the photoelectrochemical conversion efficiency of 0.75 wt.%RGO-TiO2 composite anode increases by 30.2% compared with that of ordinary TIO _ 2 particles. The RGO-TiO _ 2 composite photoanode has a thickness of 16 渭 m. In addition, we also studied the effect of graphene size on the efficiency of the cell. It was found that the use of smaller graphene can improve the adsorption capacity of dyes, thus obtaining a higher conversion efficiency. The effect of photoanode addition of RGO on the parameters of the battery is discussed. The electrical properties of the battery are further studied. It is found that the improvement of the efficiency comes from the improvement of the photoelectron transport ability of graphene and the reduction of the number of the composite reactions. The electron life is prolonged. However, graphene prepared by reduction process is prepared because it is first oxidized to graphene oxide and then reduced to graphene during the preparation process. However, the process of oxidation and reduction will produce defects in the graphene lamellar layer, resulting in the degradation of the quality of graphene. Reducing conductivity ultimately limits battery efficiency. In order to solve the above problems, we used simple liquid phase ultrasonic stripping graphite to obtain graphene (EGS), and then mixed TiO2 nanoparticles to prepare EGS-TiO2 composite photoanode. Because EGSL has fewer defects than conventional RGO, Raman ID/IG~0.256 is much smaller than RGO1.128EGS can achieve higher electron mobility and achieve higher conductivity. The conductivity of EGS is nearly twice that of RGO, and the work function (4.51 EV) is exactly between titanium dioxide and conductive glass, which is beneficial to the electron transfer. EGS-TiO _ 2 photoanode achieves 8.24% conversion efficiency. Compared with the same preparation conditions, the RGO-TiO2 photoanode increased by 19%. The improvement of efficiency comes from the fact that EGS has less in-plane defects. Compared with RGO or the photoanode with only TiO2, it can achieve better photoelectron transmission with better conductivity.
【学位授予单位】：钢铁研究总院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TM914.4;TQ127.11
[Abstract]:Dye-sensitized solar cells have great potential for large-scale production because of their advantages of low cost, high efficiency and easy to manufacture. Although 13% optoelectronic conversion efficiency has been achieved, there is still a need to further improve the efficiency from an application point of view. The main bottleneck limiting the efficiency improvement of dye sensitized solar cells is that the photogenerated electrons in the photoanode are due to the defects and weak connections between the nanoparticles during the transmission through the TIO _ 2 particles. A large number of complex reactions occur during the transmission of electrons, limiting the output current of the battery. In order to improve the connection between nanoparticles and improve the photoelectron collection efficiency of photoanode, thus achieving a higher photoelectric conversion efficiency. Graphene, a stable two-dimensional nano-carbon material, is introduced as a charge transfer material into the photoanode of a dye sensitized solar cell because of its conductivity hundreds of millions of times higher than titanium dioxide. In this paper, we mainly explore the preparation of graphene titanium dioxide complex containing high conductivity graphene and uniform composition under green nontoxic conditions, and make it into a dye sensitized solar cell photoanode, which is used to enhance electron transport in photoanode. Improve battery efficiency. We proposed a simple method to prepare graphene-titanium dioxide photoanode under mild conditions. Under normal temperature, vitamin C was used as reducing agent, and simple agitation and centrifugation were used to prepare graphene-titanium dioxide photoanode. Graphite-titanium dioxide nanocomposites were prepared by reducing graphene oxide to graphene (RGO). RGO-TiO2 photoanode with different content was prepared by adjusting the content of RGO in the complex. Under the condition of the same film thickness, the highest conversion efficiency can be obtained when the photoelectrochemical conversion efficiency of 0.75 wt.%RGO-TiO2 composite anode increases by 30.2% compared with that of ordinary TIO _ 2 particles. The RGO-TiO _ 2 composite photoanode has a thickness of 16 渭 m. In addition, we also studied the effect of graphene size on the efficiency of the cell. It was found that the use of smaller graphene can improve the adsorption capacity of dyes, thus obtaining a higher conversion efficiency. The effect of photoanode addition of RGO on the parameters of the battery is discussed. The electrical properties of the battery are further studied. It is found that the improvement of the efficiency comes from the improvement of the photoelectron transport ability of graphene and the reduction of the number of the composite reactions. The electron life is prolonged. However, graphene prepared by reduction process is prepared because it is first oxidized to graphene oxide and then reduced to graphene during the preparation process. However, the process of oxidation and reduction will produce defects in the graphene lamellar layer, resulting in the degradation of the quality of graphene. Reducing conductivity ultimately limits battery efficiency. In order to solve the above problems, we used simple liquid phase ultrasonic stripping graphite to obtain graphene (EGS), and then mixed TiO2 nanoparticles to prepare EGS-TiO2 composite photoanode. Because EGSL has fewer defects than conventional RGO, Raman ID/IG~0.256 is much smaller than RGO1.128EGS can achieve higher electron mobility and achieve higher conductivity. The conductivity of EGS is nearly twice that of RGO, and the work function (4.51 EV) is exactly between titanium dioxide and conductive glass, which is beneficial to the electron transfer. EGS-TiO _ 2 photoanode achieves 8.24% conversion efficiency. Compared with the same preparation conditions, the RGO-TiO2 photoanode increased by 19%. The improvement of efficiency comes from the fact that EGS has less in-plane defects. Compared with RGO or the photoanode with only TiO2, it can achieve better photoelectron transmission with better conductivity.
【学位授予单位】：钢铁研究总院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TM914.4;TQ127.11
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